مسند امام احمد بن حنبل · Hadith 674

It was narrated that 'Ali (RA) said: " Ihe Muslim has the right to six acts of kindness from his fellow Muslim: he should greet him with salam when he meets him; he should say 'Yarhamukallah (may Allah have mercy on you) when he sneezes; he should visit him when he is sick; he should respond to him when he invites him; he should attend his funeral when he dies; he should love for him what he loves for himself; and he should he sincere towards him when he is not present."